wifi: ath9k: fix LNA selection in ath_ant_try_scan()

In 'ath_ant_try_scan()', (most likely) the 2nd LNA's signal
strength should be used in comparison against RSSI when
selecting first LNA as the main one. Compile tested only.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20231211172502.25202-1-dmantipov@yandex.ru

ath9k: fix RX_STAT_INC() etc macros

A couple of macros that deal with statistics in ath9k rely on the
declaration of the 'sc' variable, which they dereference.

However, when the statistics are disabled, the new instance in
ath_cmn_process_fft() causes a warning for an unused variable:

drivers/net/wireless/ath/ath9k/common-spectral.c: In function 'ath_cmn_process_fft':
drivers/net/wireless/ath/ath9k/common-spectral.c:474:20: error: unused variable 'sc' [-Werror=unused-variable]

It's better if those macros only operate on their arguments instead of
known variable names, and adding a cast to (void) kills off that warning.

Fixes: 03224678c013 ("ath9k: add counters for good and errorneous FFT/spectral frames")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

ath9k: add support for reporting per-chain signal strength

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Add support for AR9565 v1.0.1 LNA diversity

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Remove ath_ant_comb_update()

During a HW reset, the diversity config is programmed
in the set_board_values() eeprom callback, there is no
need to do it again by calling ath_ant_comb_update().

Fixed antenna support is not fully handled for 1-stream
cards, it can be done later.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Rename ath9k_hw_antctrl_shared_chain_lnadiv

Use "ath9k_hw_set_bt_ant_diversity" instead.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Cleanup WLAN/BT RX diversity

For single-chain WLAN+BT cards, the BT antenna can be used for
WLAN RX when the BT interface is disabled. Rename the modparam
"antenna_diversity" to "bt_ant_diversity" to clarify this.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Fix antenna diversity for CUS198

CUS198/CUS230 need a few tweaks in the antenna diversity
algorithm to accomodate RSSI variation. Add a couple
of knobs to control low RSSI threshold and fast antenna
diversity bias values.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Add information about antenna diversity

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Add statistics for antenna diversity

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Use a subroutine to calculate ALT ratio

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Simplify checks in quick_scan

There is a function to do a ratio comparison for ALT,
so make use of it.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Use a helper function for checking LNA options

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Use a subroutine to try LNA switch

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Add ALT check for cards with GROUP-3 config

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Use a subroutine to check for short scan

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Do a quick scan only when scan_not_start is true

Right now, it is being done for all cases.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Add a module parameter to enable diversity

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k_hw: Add antenna diversity group for AR9565

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Remove redundant variable assignment

Set main_gaintb and alt_gaintb once instead of zero'ing them
in every case.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: Move LNA code to antenna.c

And use a helper function to setup antennae after a reset.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>